Study On Preparation And Optical Gas Sensing Characteristics Of Ti-doping Nano Tungsten Oxide Films

Nano tungsten oxide films material is a important functional material, It is investigated and exploited broadly because of its gaschromic property, electrochromic property, photochromic property, etc.Especially gaschromic property is applied to gas sensors extensively.The Tungsten oxide thin films were deposited on glass substrates by DC- reactive magnetron sputtering technology and then Heat treated at 350℃, 450℃and550℃. Firstly, preparative methods and application of tungsten oxide films were summarized. Secondly, theory, technological process and progress of DC- reactive magnetron sputtering technology were introduced and analyzed, and theory, characteristic and important factors on DC-reactive magnetron sputtering were presented in detail. Optical properties,micro-structural properties of Tungsten oxide films, Ti :WO₃ thin films were studied. The films were characterized with X-ray diffraction (XRD),ultraviolet visible transmittance Spectrophotometer (UV-Vis) and step devices. As results of study, With the increase doping of Ti,the mean grain size decreases. With the increase of Partial pressure of oxygen,the thickness of thin films decreases, and grain size increases, As the Heat treated temperature increased, the general crystal particles size increased, and the Tungsten oxide thin amorphous films began to crystallize. And finally, the Tungsten oxide thin films with hexagonal structure were obtained, which grew merit on the direction of (200). So we finally found the proper technical condition.The reliability and repeatability of Tungsten oxide film sensitive to NO₂ were also researched. All the films in various deposited conditions were detected and analysised. Finally, the significant factors which affect the properties of the films were analyzed particularly. Firstly, Tungsten oxide film which were doped Ti with different amount,were employed for the measurement of optical gas sensing properties by using nitrogen dioxide,Then found the optimal partial pressure of oxygen, heat treatment temperature and other best technical parameters. The results show that the films with doping amount 4% ,partial pressure of oxygen is 30% and without heat treatment ,were performance excellent of optical gas sensing characteristics in NO₂ gas, Finally, the experiment of recovery of the samples we did, it is show that the films in the range of 380nm to 550nm region has better recovery.So, the study for laid the foundation for new generation of "optical - gas" sensor.